1. Field of the invention
The present invention relates to a mechanism for beginning and ending the unlocking numeral-combination changing operation of a combination lock, more particularly one, which, while being moved from the position allowing the combination-changing action back to the normal position, cannot cause unwanted rotational movement of the dials, thus preventing accidental change of the combination after it has been changed to a predetermined one.
2. Brief Description of the Prior Art
Referring to FIG. 12, a conventional changeable combination lock includes:
a lock bar 81, which has a cone-shaped head, a lock rod 813 joined to the head; the cone-shaped head having a trench 812; the lock rod 813 having spaced apart teeth 8131, and spaces 8132 between the teeth 8131;
a spindle 84, which has a convex edge 841 at a front end, a channel 842 having an upper opening, and flat sides on a bottom and an upper side of a rear end thereof, on which a fixing hole 843 is formed;
a thimble 85, which has a round disk, and an annular wall around the disk; the disk having a through hole 853, two protruding blocks 851, 851 at opposite portions of the inward side thereof, and a stopping block 852 on the outward side thereof;
several dials 87, each of which has numerals 8705 spaced out on an outer side, an inserting hole 8701 on the middle, spaced teeth 8702 projecting towards the center thereof, spaced convexly curved surfaces 8704, and withholding spaces 8703 between the teeth 8702;
several tooth dishes 871, each of which has an inserting hole 8711, a gap 8712, and spaced apart convex teeth 8713 on an outward side thereof;
a spring 844 for biasing the tooth dishes 871 to an engaged position where the convex teeth 8713 engage the teeth 8704 of corresponding dials 87 so that the tooth dishes 871 will be turned together with corresponding dials 87;
a barrel 83, which has a cone-shape, a cavity 831, a hole 832, a pin hole 833 in communication with the hole 832, and a trench 834; the hole 832 having flat upper and lower sides;
a setting push ring 86, which has a gap 861, and protruding edges 862 at two opposite portions of an outward side thereof; each of the protruding edges 862 having a slope 8621; and,
holding elements 88, each of which has a gap 8801, and two opposite engaging protrusions 8802; the holding elements 88 being used for holding respective sliding elements 881 in position, each of which has a gap 8811, two recesses at two opposite portions of an outward side thereof,
the spindle 84 being passed through the thimble 85, the setting push ring 86, a first one of the dials 87, a first one of the tooth dishes 871, a first one of the holding elements 88, a first one of the sliding elements 881, a second one of the dials 87, a second one of the tooth dishes 871 and so on, and being finally passed through the spring 844 and inserted into the hole 832 of the barrel 83; the protruding blocks 851 of the thimble 85 being pressed against the slopes 8621 of the setting push ring 86; the teeth 8713 of the tooth dishes 871 being engaged with the teeth 8702 of respective dials 87; a pin 835 being inserted into the pin hole 833, and the fixing hole 843 to securely join the spindle 84 to the barrel 83.
Thus, the lock bar 81 is locked with the tooth dishes 871, and incapable of separating from the spindle 84 when the dials 87 are turned off the unlocking numeral combination.
To change the unlocking numeral combination, first the thimble 85 is turned so that the protruding blocks 851 of the thimble 85 slide on the slopes 8621 of the setting push ring 86 to push the setting push ring 86, and in turn, the tooth dishes 871 are disengaged from the respective dials 87. Then, the dials 87 are turned so that orientation of the dials 87 relative to the gaps 8712 of respective tooth dishes 871 is changed. Finally, the thimble 85 is turned back to the original position for allowing the spring 844 to force the tooth dishes 871 to engage the respective dials 87 again.
Referring to FIG. 3, another conventional changeable combination lock is substantially like the above one except having folded elastic wires 985, and holding elements 98 instead of the sliding elements 881 and the holding elements 88; the folded elastic wires 985 are held in position by means of the holding elements 98.
Both the conventional changeable combination locks are found to have a disadvantage that when the thimble 85 is being moved back to the normal position after the numeral combination-changing action, undesired rotational movement of the dials are prone to be caused accidentally. In other words, accidental change of the combination is likely to happen after the combination has been changed to a predetermined one, causing the user a lot of inconvenience.
It is a main object of the present invention to provide a mechanism for beginning and ending the unlocking-numeral combination-changing operation, which is structured such that movement thereof cannot cause rotational movement of the dials accidentally.
The present mechanism includes a pressing block fitted to the front end of a spindle of a changeable combination lock and associated with a pad. The pad has posts contacting a most front one of several spring-loaded tooth dishes, which separably engage respective dials each having numerals spaced on the outer side.
The pressing block is pressed towards a rear end of the spindle so that the posts force all the tooth dishes to move rearwards to disengage respective dials; thus, the dials can be turned relative to the tooth dishes for changing the unlocking numeral combination to a new one; the pressing block is pressed slightly down right after being pushed rearwards so that it can be held in position allowing the tooth dishes to stay disengaged from respective dials. When the combination changing operation is finished, the pressing block is pushed back to the original position for the tooth dishes to engage respective dials again.